DE1945179C - Refractory building material for ladle linings - Google Patents

Description

The invention relates to a refractory building material for pouring ladle linings in the form of ramming material or shaped bricks made of refractory materials with added graphite. Such a building material is from the Publication "Lecture Hall for Ceramics, Gias, EmaiI", 1960, p. 53, known the graphite-Schaniotte-shaped stones describes, while from the publication "Feuerfest künde" by Harders / Kienow, 1960, S. 539/540, a ramming compound for ladle linings is known, but which is less durable than the therefore called firebricks to be preferred

ίο will. This reference insists on the The necessary care is indicated in the lining of the pan, which would otherwise only lead to a short shelf life and deterioration in the quality of the cast.

Indeed, ladle lining requirements are problematic. As important, ^ e properties one demands:

1.Resistance to attack and reaction with molten slag,

2. resistance to attack by molten steel,

3. Resistance to sudden temperature changes, which would otherwise lead to premature failure and could lead to inclusions in the cast metal, and

4. low thermal conductivity.

The residence time of the molten steel in ladles is usually relatively short, resulting in very sharp temperature gradients across the refractory lining. This makes it impossible to establish any kind of equilibrium near the boundary layer in contact with the molten metal. For example, in a 19 cm thick ladle lining, the temperature is about 2, f <"m distance from the interface at an initial steel temperature of about 1580C after a few minutes only about 260 ~ C and reached only about 65O ⁰ C after 1 hour.

Most steel is made with a basic slag and it would therefore seem logical that the pan lining would also be basic. However, no basic refractory product was available, which had the required resistance to sudden changes in temperature, urr. the sudden and extreme changes in temperature when loading and emptying the To withstand a pan, as can be seen in the cited reference "Feuerfestkunde".

Because of the need for a suitable basic refractory Materials, steelmakers have decided to use acidic refractory materials, such as refractories Fireclay rope, forced. Although the softening point of these stone materials is so low that theirs Use under such environmental conditions seems to be ruled out because of the short residence time and the abovementioned abrupt temperature range, their use is possible. The usage However, of firebricks has various disadvantages compared to monolithic or tamped Linings, such as B. the need for special forms and lettering work. Another with firebricks related problem is the sealing of the joints between the stones for prevention the penetration of molten metal and slag, as a result of which it becomes very dimensionally stable Stones required.

3 4

The object of the invention is to provide a building material of the material according to the invention as a function

to create the type mentioned at the outset, which as a stamping of various factors, such as. B. the type and

mass can be processed - which is of course its use- Form of the special components used,

dung in the form of shaped stones does not exclude - vary.

is compatible with basic slag and in its 5 For example, the mixture can be in the following

Lifetime (number of batches) moving in competitive areas:

should be. Weight parts

According to the invention, this object is thereby achieved by refractory batch particles 40 to 95

solved that on the particles of the granules before- kyanite 0 to 20

lying refractory materials first a phos- io graphite 2 to 40

phate coating, on top of which a coating of binding clay, also binding clay 2 to 30

another graphite coating and another phosphate 1 to 15

Phosphate coating is applied. The making of water 1 to 15

Building material can be done according to the invention so that

those coated with the first phosphate binder coat

seen granules with in relation to their core materials and with optimal properties has ioi-

large fine clay can be mixed so that according to the following composition:

In the development of the Bir i'stun coating of the mixture of graphite weights

Squat are added and that the mixture after fired slate 64.0

Formation of the graphite coating again.-, a phosphate 20 kyanite 5.2

Binder added wire ¹ . The result is a Norwegian graphite B, 9

Ready-to-use, flowable (pourable), in the refractory binding clay 10.3

Material easily pounded into the pan. Let it be aluminum! Umpho:; phat 6.5

pointed out that from de USA.-Palentschrift Wasser 5.1

3 285 7b3 a refractory ramming mass known per se 25

which, however, is not flowable (free-flowing), «.onderr. Fired shale, the preferred fire plastic and therefore more difficult to process. In addition, solid base material for the construction in accordance with the designation it differs significantly in its ingredient, is made from refractory slate, The composition of the building according to the invention is a hard or flint-like refractory clay stuff, in particular it does not contain graphite. 3 ° and occurs as an unstratified massive rock,

In a preferred embodiment, which lacks in particular a natural plasticity, and refractory ladle lining material according to which shows a shell-like fracture. This material invention on the basis of rather coarse, is burned or calcined to produce its own refractory support material, which can be removed from shrinkage, and then broken down to the geMaterials, such as baked slate, alumina, 35 desired particle size. A typical zirconia, silica or silica, chrome ore, and chemical analysis for calcine ^: hard or calcined mullite, can be selected. The first on the fire-shale shows the following composition: the solid support material applied is aluminum phosphate or another phosphate, the content of which is%

Phosphoric acid. After applying the phosphate 40 clay 44.37

The mixture particles are coated with silicon dioxide ^ ¹ ^

sought-after materials, such as binding clay and kvanite or litan _, 6 /

a similar material, coated. The phosphate. Remote oxide 0.73

Binding clay and kyanite form the matrix or carrier potassium oxide 0.05

mass, which the refractory base materials to 45 Magnesium oxide 0.1 i

closes and the gaps and pores between its alkali constituents 0.38

Particle fills. Then a coating is made

Graphite applied to which another phosphate- The particle sizes of the refractory base material; » Protective layer follows. The graphite is highly refractory, although s ^; e is not a critical factor preventing the adherence of the iron and the slag 50, generally between 0.15 and 6.75 mm, with the lining and mainly contributing to the greater proportion being between 0.3 and 6.75 mm. desired properties of the mixture. The A typical particle size analysis of calcined graphite, however, at temperatures of about Scbief non for use in erfind ¹ J ig HOO ⁰ C, as on the surface of the lining as follows:! Rule, easily oxidized. This oxidation would be the 55th

Properties of the lining, which add to the graphite- Grain size (mm) Sieve residue m * "

are to be attributed, such as the ability to an adhesion of 6.75 0.0

To prevent iron and slag from destroying. From 4.75 14.7

for this reason the coating is made of a phosphate 3.40 18.0

provided over the graphite. The phosphate lv.it also 60 2.40 9.3

the function, of the refractory mix its strength 2.00 5.3

ness to ENVA 65 ⁰ C below the melting point to ER- 0.85 11.6

keep. Aluminum phosphate e.g. B. is at increased 0.60 13.4

Temperatur.n the most elastic, gives a product 0.42 14.0

nis with an excellent contradiction 65 0.30 5.3

against chipping and sudden temperature changes - 0.21 3.3

rungeii and ensures high strength. 0.15 2.3

The composition of the pan lining screen passage at 0.15 2.8

It should be noted that the above grain size examples include bentonite and plastic, kaolinite

division contains two distinct groupings, one containing materials such as kaolin,

with relatively large particles and the other A preferred binding clay is a plastic fire-

with a concentration of fine particles. The medium-solid clay of the kaolinite type, which is the following typical

large particles between these two groups has 5 chemical analysis:

are kept to a minimum. This particular salary in%

Combination of particle sizes is such that the clay is 41.57

large particles collide and the fine silica 53.96

Particles fill the gaps without the large particles of titanium 2.15

to push apart. Such an arrangement in io ferric oxide 1.38

Connection with the appropriate division of an calcium oxide 0.09

Partly large and small particles gives a final pro-magnesium oxide 0.17

high density product, which is desirable to make the one alkali constituent 0.64

penetrate the molten metal and slag

to withstand in the refractory lining. 15 Diesel binding clay is dried and then so far

Kyanite is therefore ground a desired component, that, because he light ⁰ C by means of a DIN-sieve-1,5 hindurchder mixture when heated above UOO. Kaolin can expand its volume for the less pure kaolinitin. This expansion takes place in hailigen refractory clays, f; 'lis a at about the same temperature at which the refractory binder oucr material is required. Binding clay begins to shrink, so that otherwise it is possible for the binding clay in the mixture to fill the gaps between the refractory mixtures. The kyanite also reacts with the liquid particles to fill and the refractory mixture phase, which ^{begins to plasticity and adhesiveness and the mass at temperatures above about 1100 0} C, forming a more viscous content at the increased temperatures to ver-glass phase. These factors all improve the borrowing.

ability of the material in the hot state. The Kyanil The preferred one used in the invention

also contributes to the fire resistance djr matrix or graphite is Norwegian graphite, a in Norway

Carrier that has the lowest melting temperature of the natural material to be found. The graphite

Has ingredients in the final product. Other mineral is broken and the graphite through

Refractory components made from natural aluminum 30 flotation separated from the gangue, dried and

Silicate that expand when heated can be classified as follows:
found in place of kyanite, such as Andalusii and Sillimanit, although these materials
do not stretch as much as kyanite.

The kyanite is preferably crushed raw Virginia kyanite, an aluminum silicate mineral with approximately d.T the following chemical composition:

Salary in ⁰ u

Alumina 56.3

Silicon dioxide 41.5 * °

Titanium 1,2

Ferric oxide 0.8

Calcium oxide 0.1

Magnesium oxide 0.1 _t ,,,, ",,,. ,,,., ·,

45 The carbon content of the resulting material

A suitable particle size analysis for the kyanite ^lie 8 ^l * · 'approximately 90%. This particular nor-

hai the following data: Wegische graphite is preferred because of its large flake structure and its relative softness

Grain size (mm) sieve residue in »/ 0 _h eit as well as because of its resistance to oxy-

0> ° 5 0.0 ^ ₀ dation in contrast to those obtained elsewhere

° ' ⁶ °. ^] Graphites.

0'42 7.8 Q _he coating of the refractory base material with

"'3 15.7 d _s various coatings is carried out such that the

0-21 31.1 Particles do not adhere to each other and not even one

"> 15 22.2 _{55 form a} sticky mass instead of the desired

0.1 10.7 separated, flowable particles. This is achieved

0.075 6.6 by using a pelletizing device,

0'05 3.9 preferably with an inclined, rotating plate.

Sieve passage at 0.05 1.9 Such a device is, for example, through the

60 Dravo Corporation under the name »Dravo-

The term "binding clay" used here is intended to sell the Lurgi pelletizing plate or disk. the

include those materials that a large binding pellet size can pass with such a device

have the ability and are able to monitor the speed of rotation, the

non-plastic components are adjusted to the connection angle and the point of application,

the. The binding can be selected from substances 65 The classification effect of the plate or the

be that have this ability to bind. The on the disk according to the particle size stratifies the particles

The most common group of binding clays are on the bottom of the trough or pan and provide the

the plastic or refractory bindctonc. Others manufacture pellets continuously in a very tight space

Grain size (min) Sieve residue in 7th 0.85 0.0 0.6 0.1 0.42 0.6 0.3 5.0 0.21 13.6 0.15 21.2 0.1 21.6 0.075 17.4 0.05 5.0 Sieve passage at 0.05 15.2

Size range. Allow the plates or slices it is also for the operator to observe the materials during the pelletizing process Zii. This Pelletizing disks require little maintenance and still work with high throughput rates.

The mixture is prepared by first weighing the fired slate or other refractory bulk material and adding to the surface of the inclined Disc of the Pelietisiervorrichtung is conveyed, which at a speed of about 18 rev / min. rotates at an angle of inclination of 45 °. An aqueous slurry is formed from the aluminum phosphate, and a portion is added to that on the circulating Disc rolling refractory mix sprayed. the Binding clay is then fed onto the surrounding S: heibe and adheres to the already refractory Binder coating present in the mixture. The kyanite and graphite will then be more similar Way applied as a coating on the particles. The rest of the aluminum phosphate water slurry is then on the particles on the disc are sprayed to form the top protective coating over the Graphite. After a short tumbling time of about ίο 3 minutes on the disc, the material, which is not agglomerated and is still present in separate particles, discharged from the disc to form a Packing device conveyed and packed in multi-walled, polyethylene-coated bags or cardboard boxes.

Some typical properties of the refractory material produced are listed below:

Clay

Silicon dioxide ...

Ferric oxide

titanium

Calcium oxide

Magnesium oxide. Alkali constituents Burning losses ... humidity

Chemical Analysis after

Deliver

36.27

41.96

0.69

1.98

0.07

0.09

0.34

13.80

5.80

dried

38.50

44.49

0.73

2.10

0.08

0.10

0.36

13.64

burned

43.16 49.87 0.82 2.36 0.09 0.11 0.40

Physical Properties

Investigation ^ * / · Linear Modulus of rupture
space Modulus of rupture
at tcmperature change temperature Temperature, ° C kg / cm ' kg / cm 110 -0.2 41.3 540 -0.2 38.5 815 -0.2 21.0 23.8 1100 -0.3 21.0 33.95 LÄ.W 0.2 24.5 156 1370 + θ] ό 26.6 3.92 1480 + 0.8 25.9 2.38 1600 + 1.0 28.0 - 1650 + 1.2 56.7

The angle of contact between the molten slag and the molten metal and those with Graphite coated refractory particles are high, causing wetting and capillary soaking the lining is prevented by the molten components. This leads to a low chemical attack on the refractory lining. the Thermal conductivity of the liner is poor, and the molten metal does not solidify without it further and also does not form a pan residue in the pan because of the non-wettability of the building material, which is able to withstand sudden temperature changes without chipping and a high strength Above the usual temperature range has to withstand the impact of the molten material occurring To withstand the stream of metal the first time it enters the empty pan. The refractory building material shows also low shrinkage. One of the particularly outstanding features of the refractory ladle lining construction material according to the invention is its flow consistency and the fact that it is in the form of separate particles which, according to the Removal from the packaging can easily be conveyed to a shape in the pan, such as for example wise on a vibratory conveyor. The refractory Building material is then tamped down according to the shape of the pan, forming a dense, non-porous lining. Neither special shapes nor any cutting operations are required, such as which is otherwise the case with linings made up of individual stones; of course the material can but can also be used to shape refractory bricks, and then turn it into the desired Molded and placed at a temperature of about 260 ° C is dried.

The special components and ingredients and the process for producing the refractory building material allow the incorporation or inclusion of graphite with an elastic protective coating for the purpose Prevention or retardation of the oxidation of graphite. The wear and tear of the lining material also progress comparatively slowly away. The fireproof building material dries easily and neither cracks nor emerges when it dries Blow. The modulus of rupture under various conditions is also high, as stated above, which results in a high resistance to erosion at operating temperatures

Claims (7)

Patent claims: 1. Refractory building material for ladle linings in the form of rammed earth or shaped stones made of refractory materials with added graphite, characterized in that the particles present in granules refractory materials first ei.) phosphate coating, then a coating of binding clay, further Another graphite coating and another phosphate coating is applied. 2. Refractory building material according to claim 1, characterized by a composition of about 40 to 95 parts by weight of refractory aggregate or base material, 1 to 15 parts by weight of a phosphate binder, 1 to 15 parts by weight of water, 2 to 30 parts by weight of graphite and up to 20 parts by weight a natural aluminum silicate such as kyanite, andalusite and sillimanite. 3. Refractory building material according to claim I, characterized in that the refractory material Fired slate is used as the base material. 4. Refractory building material according to claim 3, characterized in that the phosphate is an aluminum phosphate is used. 5. Refractory building material according to claims 1 to 4, characterized in that ah refractory base material alumina (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), quartz, chrome ore and mullite and kaolin or bentonil as a binder: are used. 6. Process for the production of the building material according to Claim 1, characterized in that the provided with the first phosphate binding agent over / ug Granules are mixed with binding clay that is fine in proportion to their grain size, that after formation dvs binding concrete coating of the mixture graphite flakes be added and that the mixture after formation of the giraphite coating again Phosphate binder is added. 7. Process for the production of a refractory building material mix, especially for tamped ones Ladle linings and the like according to claim 6, characterized by the following process steps: a) Use of fired shale particles with a particle size between 0.15 and 0.75 mm, b) spraying a slurry or slurry of aluminum phosphate and water on the shale particles for the purpose of coating the particles, c) Mixing a binding clay selected from the group of refractory binding clay and kaolin with a maximum particle size up to about 1.6 mm with the coated particles their covering with the binding clay, d) Mixing graphite with a particle size of at least 0.3 mm to the particles of process step c) and e) adding more aluminum phosphate and water slurry to the particles from process step d) for producing the outer protective coating over the graphite layer.